1. Field of the Invention
The described technology relates generally to devices and methods for imaging within a body lumen, cavity or other enclosed space, and, more particularly, it relates to a single-use electronic endoscope for various uses (e.g., for arthroscopic knee surgery).
2. Description of the Related Art
Diagnosing and treating patients often involves examination of internal organs and structures. In “open surgery,” a large surgical cut or incision is made in the patient's skin and flesh. Doing so permits the doctor to see directly into and access the area being treated. However, large surgical wounds cause significant patient pain, involve use of powerful anesthetics and analgesics such as narcotics to keep the patient comfortable during and after surgery, often take significant time to heal and limit post-surgical patient activity (particularly if muscle is cut to access the treatment area).
To avoid disturbing nearby tissues, doctors use various imaging technologies to probe ducts, orifices, bodily openings, or other spaces. Such devices allow remote viewing of difficult-to-access spaces without large incisions, and have been referred to by different names, including angioscope, arthroscope, borescope, cystoscope, endoscope, and fiberscope.
Arthroscopy is increasingly popular. Common arthroscopic procedures examine and treat damaged tissue within various body joints, such as by removal or repair of torn cartilage portions of the meniscus, ligament, and tendon reconstruction, removal of loose debris, and trimming or shaving damaged articular cartilage. More than 4 million knee arthroscopies and more than 1.4 million shoulder arthroscopies are performed worldwide each year, according to the American Orthopedic Society for Sports Medicine. Other joints such as the shoulder, elbow, ankle, hip, and wrist can also be viewed through arthroscopy.
An endoscope has a light source and a camera. Fiberscopes (or fiber-optic endoscopes) include both illumination fibers or light guides to direct light which illuminates the field of view and imaging fiber bundles to transfer the image of an illuminated area to the camera. In diagnostic arthroscopy, after introducing the device into the patient's joint, the doctor shines light into that joint. The camera provides an image of the joint, which is then viewed on a video monitor. By viewing the joint of interest through the device, the doctor does not need to make a large incision. Sterile fluid can be used to expand the joint, which increases visibility in the joint area and makes it easier for the doctor to work. These single-port diagnostic procedures have been performed in a doctor's office and “walk in” or ambulatory surgery centers, e.g., using a 2.0 mm fiber optic arthroscope. Routinely these diagnostic procedures are performed under local anesthetic to numb the area being examined and the patient remains awake throughout the procedure.
Other endoscopes are used to actively treat or operate on patients' joints. The doctor inserts the endoscope into the joint. Additional holes or incisions can be provided to allow other tools to be used during the surgery to cut, shave, remove particles in the joint, or repair tissue. Alternatively, the endoscope can include a working channel that allows surgical tools (e.g., biopsy forceps and other tools) to slide in and out of the joint.
Such operative or therapeutic arthroscopic surgery has limitations. Operative endoscopes with working channels for arthroscopy are typically 3-4 mm in diameter. This makes the overall procedure more invasive and more taxing on the patient than when smaller diagnostic endoscopes are used.
Operational arthroscopic procedures can have life-threatening risks. General anesthesia, with its attendant risks, can be used, particularly for more interventional operative arthroscopy. To avoid accidental patient infection, doctors use sterile techniques and equipment.
Such risks are not trivial. The Ronald Reagan UCLA Medical Center is a leader in performing the latest minimally invasive endoscopic procedures. In February 2015, as many as 179 people at that hospital were exposed to drug-resistant bacteria while undergoing endoscopic procedures. According to press reports, seven of those people become infected with methicillin-resistant staphylococcus aureus (MRSA), and two of those patients died.
The U.S. Food & Drug Administration issued a general warning to all health providers regarding the use of medical endoscopes for complex endoscopic procedures. The complex design of some endoscopes impedes the ability to clean, disinfect, and sterilize these reusable devices.
Previously known endoscopes suffer a number of disadvantages, including significant initial cost and the need for sterilization after each use. Such sterilization procedures are time consuming and lead to further expense.
U.S. Pat. No. 6,840,909 to Gatto describes a device for removal of tissue and cells from breast ducts. At its distal end, the device has a rigid or semi-rigid cannula tube. This cannula has an outer diameter ranging from 0.5 mm to approximately 1.2 mm, and acts as a guide tube for an endoscope. To obtain biopsy cells and tissue, a physician manipulates the cannula tube itself to scrape cells free of tissue. Injecting saline into the area followed by application of a vacuum withdraws the water and scraped cells from the patient.
U.S. Pat. No. 8,323,181 to Mukherjee describes an endoscope with an insertion end that is about 1 to 2 mm in outer diameter. FIG. 5 shows the tip of the insertion end of the endoscope, which has a flexible polyamide sheath. Enclosed within the sheath are an image-bundle focus lens, two laser-focus lenses, and optical fiber bundles used for illumination.
U.S. Pat. No. 8,858,425 to Farr describes an endoscope with removable, pluggable, and disposable optoelectronic modules. FIG. 7b shows a surgical tool 750 that can be inserted through the disposable cannula 700 after the distal end 702 has been inserted inside the body. That distal end 702 is made flexible so that, after insertion into the patient, the entire distal tip 702 of the cannula can be expanded radially.